Bacteria filters with transparent housings

ABSTRACT

A bacteria filter for use in anesthesiology and respiratory care systems to filter fluid flow at a desired point in a system. The filter includes an enlarged non-conductive, transparent tubular housing having a passageway therethrough and tapering at one end to a reduced tip. A conductive connector is mounted to the reduced tip and a conductive end cap is affixed to the end of the housing distal from the reduced tip. The end cap has an opening therethrough terminating in a projecting connector. A filter element is retained in the housing and a conductive portion extends between the end cap and the conductive connector to provide a conductive pathway from end to end of the filter. The connector and the projecting end cap are adapted to be mounted within a fluid flow system to permit fluid communication with the interior of the housing so that fluid flow through the system passes in one end of the housing, through the filter element and out the other end of the housing.

This is a division of application Ser. No. 765,111, filed Feb. 2, 1977,now U.S. Pat. No. 4,133,656 which is a division of Ser. No. 669,622filed Mar. 23, 1976, now U.S. Pat. No. 4,063,913, and which is acontinuation-in-part of U.S. Ser. No. 500,405 filed Aug. 26, 1974 nowabandoned.

BACKGROUND OF THE INVENTION

In anesthesia and respiratory care breathing systems, it has been foundthat it is desirable at times to filter gases or fluids prior to theirintroduction to the patient. An example of a system of this type isdisclosed in U.S. Pat. No. 3,556,097.

On occasion, certain problems occur during the filtering process whichrequire independent consideration. For example in handling certain typesof gases an electrical problem occurs which makes it desirable to have afilter which is of a conductive material to alleviate the problems.However, with known conductive materials within a reasonable cost range,there is no known material which is transparent in nature. Thiscombination leads to an additional concern. During the handling of thegases, particularly gases which have been passed through absorbers andvaporizers, during the filtering process a certain amount ofcondensation occurs as the gas passes through the filter medium. Thecondensation on a continuous basis results in a condensate build-upwhich eventually would clog the filter. With conductive housings of anon-transparent nature it is impossible to observe the condensatebuild-up within the filter and, consequently, with known systems it isnecessary to replace the filter at periodic intervals as a safetymeasure without actually knowing the extent of condensate build-up.

Carrying this concern one step further, with the filters presently inuse there is no structure which provides for removal of condensatebuild-up were it possible to observe this development. The filters couldbe used until they completely fill beyond an acceptable condensate leveland then they would have to be removed from the system.

Another consideration of the known filters for the environment underconsideration is that they are generally designed to interconnect with asystem of a predetermined arrangement. It would be extremelyadvantageous to provide a filter which is adaptable for connection witha variety of different types of breathing systems without altering thephysical structure of the filter itself.

Finally, above all, it is imperative that the filter be of low costdisposable materials so as to be compatible with general systemspresently in use which are primarily designed for single use. On theother hand, the filter should be versatile enough so that the condensatebuild-up can be removed during the single use without the necessity ofhaving to use a multiple of filters for an individual patient.

SUMMARY OF THE INVENTION

With the above background in mind, it is among the primary objectives ofthe present invention to provide a disposable filter and is designed forinterconnection with a variety of well-known anesthesiology andrespiratory care systems. The filter is adapted to receive fluid flowtherethrough in either axial direction, contains a conductive path fromend to end to alleviate electrical dangers, includes a transparenthousing to permit the observation of condensate build-up within thefilter during use, and contains a valve mechanism on the filter to draincondensate which has built up beyond a desirable level within the filterduring use thereby alleviating the necessity of use of multiple filtersfor a single patient. The provision of a conductive path along with thetransparent housing to permit observation of condensate build-up and thevalve to drain excessive condensate combine to alleviate well knownpatient safety hazards.

In summary, a bacteria filter is provided for use in anesthesiology andrespiratory care systems to filter fluid flow at a desired point in thesystem. The filter includes an enlarged non-conductive, transparenttubular housing having a passageway therethrough and tapering at one endto a reduced tip. A conductive connector is mounted to the reduced tipand a conductive end cap is affixed to the end of the housing distalfrom the reduced tip. The end cap has an opening therethroughterminating in a projecting connector. A filter element is retained inthe housing and a conductive portion extends between the end cap and theconductive connector to provide a conductive pathway from end to end ofthe filter. The connector and the projecting connector are adapted to bemounted within a fluid flow system to permit fluid communication withthe interior of the housing so that fluid flow through the system passesin one end of the housing, through the filter element and out the otherend.

With the above objectives, among others, in mind, reference is had tothe attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of the filter of the invention in operableposition within a representative anesthesia breathing circuit;

FIG. 2 is a sectional elevation view of the filter of the invention;

FIG. 3 is a cross-sectional view of the filter taken along the plane ofline 3--3 of FIG. 2;

FIG. 4 is a cross-sectional view of the filter taken along the plane ofline 4--4 of FIG. 2;

FIG. 5 is a cross sectional view of an alternative form of the filter ofthe invention;

FIG. 6 is a cross sectional view of a second alternative form of thefilter of the invention;

FIG. 7 is an end sectional view thereof taken along the plane of line7--7 of FIG. 6;

FIG. 8 is a cross sectional view of a third alternative form of thefilter of the invention;

FIG. 9 is an end sectional view thereof taken along the plane of line9--9 of FIG. 8;

FIG. 10 is a plan view of a fourth alternative form of the filter of theinvention; and

FIG. 11 is a cross sectional view of a fifth alternative form of thefilter of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Filter 20 is depicted independently in FIGS. 2, 3 and 4 and is shown incooperation within a conventional well known type of anesthesiabreathing circuit 21 in FIG. 1. Filter 20 is adapted to pass flowtherethrough in either direction and is open at both ends. One end offilter 20 is connected to a corrugated conduit 22 which passes directlyto a patient breathing mechanism 23. The other end of filter 20 isconnected in line to a source of gases for filtering prior tointroduction to the patient. In a conventional apparatus as shown, thegases may originate in part from an exhalation conduit 24 passing fromthe breathing mechanism 23 and entering through a check valve into abreathing bag 25. The exhalation gases then pass from breathing bag 25into an absorber apparatus 26 for absorption of liquid to enhance thegases for reception by the patient. Monitoring the passage frombreathing bag 25 to absorber apparatus 26 are appropriate valve engagingapparatus such as pressure relief valve 27, exhalation check valveassembly 28, and pressure gauge 29. Appropriate conduit means areprovided to guide the gases from the breathing bag to the absorberapparatus as monitored by valves and gauges as discussed above.

The gases exit absorber apparatus 26 and are passed to a vaporizer 30through an appropriate conduit 31. An inlet 32 is provided along conduit31 for introduction of fresh gas to be mixed with the gas from theabsorber apparatus 26. The mixture is then vaporized in a well knownmanner in vaporizer 30 and is passed from the vaporizer 30 to the filter20 for filtering prior to introduction through conduit 22 and breathingdevice 23 to the patient.

Turning to consideration of the filter 20, an enlarged tubular housing31 is provided with openings at both ends. At one end the housing tapersat portion 32 until it terminates in an annular reduced tip 33. Aninternal rib extends inwardly from the inner surface of reduced tip 33for interlocking with a conductive connector 35.

The other end of enlarged tubular housing 31 contains an annular rib 36adjacent its end for facilitating interengagement with a conductive endcap 37. A projecting connector portion 38 which is tubular inconfiguration and open at both ends extends from a central location fromend cap 37 away from housing 31. End cap 37 has a plurality ofconcentric ribs extending inwardly of housing 31 with the outer rib 39having appropriate detent to interengage with rib 36 of housing 31 andthereby lock the end cap to the housing. The inner two concentric ribs40 form an annular recess 41 for reception of one end of a filterelement 42. The filter element is hollow and cylindrical inconfiguration.

Housing 31 is of a transparent non-conductive material of plastic orother conventional material having the similar properties. In contrast,conductive connector 35 and end cap 37 including projecting connector 38are of an electrically conductive material. Once again the material maybe plastic or other well known conventional substance having similarproperties.

Projection 38 and connector 35 need not be transparent in nature as longas enlarged housing 31 is transparent so that the interior chamber 43thereof can be observed at all times during operation of the filter.Both ends of filter 20 are conductive in nature in the form of connector35 and projecting connector 38 and in order to provide a conductive paththroughout the entire length of filter 20, it is necessary to provide anintermediate portion of conductive material extending between connector35 and connector 38. This may take the form of a strip of material alongthe length of housing 31 on the exterior surface thereof andinterconnected at its ends with connector 35 and connector 38. The stripmay be fastened to the outer surface of housing 31 by means of anadhesive or other conventional means. Alternatively, in the formdepicted, the conductive portion can be a finned element 44 extendingaxially through the interior of housing 31 and interengaging withconnector 35 and connector 38 at each respective end. The plurality offins 45 on finned element 44 are spaced circumferentially apart so as toincrease the contact points and assure a continuous conductive path fromconnector 38 through housing 31 to connector 35. Intermediate the endsof the finned element 44 is a circular tray 46 with an appropriateannular recess 47. Recess 47 is in alignment with recess 41 on theinterior surface of end cap 37. The two recesses 47 and 41 receiveopposed ends of hollow tubular filter element 42 and thereby mount thefilter element within housing 31 for use.

Connector 35 has an outer surface configuration which facilitates itsuse as a male connector for introduction within an appropriate conduitof a breathing system. In contrast, connector 38 is provided with innerand outer surfaces so that it is adapted to receive a male connectorelement of a breathing system. In this manner, one end of the filter isformed as a male connector element and the other end of the filter isformed as a female connector element. Fluid flow can proceed in eitherdirection through filter 20 and, accordingly, connectors 38 and 35 areinterchangeable thereby adding to the versatility of filter 20 forinterconnection within a breathing system.

The end wall of end cap 37 is also provided with an aperture 48therethrough to provide communication between the exterior of the filterand the interior of chamber 43. Normally positioned in aperture 48 is aplug 49 which seals with the walls forming the aperture to prevent fluidflow into or out of the filter. When plug 49 is positioned within theaperture a gripping portion 50 extends rearwardly from end cap 37 andexteriorly of housing 31. Consequently, plug 49 can be removed fromaperture 48 by grasping portion 50 and withdrawing the plug from theaperture. This opens a fluid access path to and from the interior ofchamber 43 and filter housing 31.

In use, connector 38 is connected to a source of gases for introductionto a patient such as vaporizer 30 and connector 35 is connected to aconduit such as conduit 22 in FIG. 1 for introduction directly to apatient's breathing device. Gases then pass through the hollow interiorof connector 35 into chamber 43 and through filter element 42. Oncethrough filter element 42 it has access to connector 35 and introductionto the patient in filtered form. During the passage of gases throughfilter 20 an accumulation of condensate will occur within chamber 43.With housing 31 being of a transparent material the condensate build-upcan be observed until it reaches an undesirable level. At that point,plug 49 can be removed to permit drainage of condensate. Thereafter theplug can be replaced and the filtering process can continue. Since thefilter is of disposable material, once the single patient use iscompleted, the filter can be disposed of. A continuous conductive pathexists from end to end in filter 20 through the interconnection ofconnectors 35 and 38 and portion 44. This alleviates the danger ofelectrical problems developing in the filter portion of the system.

For use as waterproof filter element 42, it has been found thatPurolator Grade A filter paper treated with phenolic coating and G E DryFilm 104 waterproofing agent 0.4% as developed by the Aerospace Divisionof Purolator, Inc., Newbury Park, California, is satisfactory.Naturally, other available acceptable filter material having the desiredproperties would be equally acceptable.

In general for use in anesthesia and/or respiratory bacteria filteringenvironments, certain general criteria must be met. Accordingly, filter20 satisfies the general criteria. The minimum particle size filteredshould be on the order of 0.3 microns absolute with 99+% of filterefficiency. The filter is designed to handle a variety of gases such as100% oxygen, cyclopropane/oxygen, nitrous-oxide/oxygen,ethyl-ether/oxygen, halothane (fluothane)/oxygen, methoxyfluorane(penthrane)/oxygen, air, carbon dioxide, water vapor-saturated at97°-105° F. (approximately 44 gms/cubic meter), and other anestheticsand medications.

Filter 20 for use in the desired environment is adapted to handle gasflow rates of 0-100LPM and 0-4CFM. The operating pressure is 20-50 cm H₂O. The highest acceptable flow resistance is on the order of 2 cm H₂ Oat 100LPM with an optimum flow resistance of 1 cm H₂ O at 100 LPM.

Filter 20 is designed for an acceptable shell life prior to use such as3 to 5 years and for a single patient use of approximately 8 to 24hours.

The unit is autoclavable and is capable of ethylene oxide sterilization(for example 120°-135° F., 50% humidity, 24 hours).

Housing 31 of filter 20 is designed for an approximate maximumelectrical resistance of 10,000 ohms which is not affected byanesthetics or medications.

The embodiment of FIGS. 1-4 which have been described in detail above issubject to many alternatives in design. For example, FIG. 5 shows afilter 20a which is similar in general configuration and design tofilter 20 with the difference in structure residing in the nature of theconductive path between the end cap 52 and the conductive connector 54at the opposite end. Web 56 of resilient material is provided with acentral aperture adapted to be resiliently enlarged upon the applicationof sufficient force and then to return to its initial configuration uponrelief of the force. A similar web 58 is provided in end cap 52. Thewebs are of conductive material and are designed to receive in snap-infashion the enlarged knobs on the end of a central post 60 extendingaxially through the center of the filter. The post is also of conductivematerial and has a knob 62 at one end and a knob 64 on the other endwith each knob adapted to snap into position within a corresponding web.Intermediate the ends of the post is a centrally located disc 66 ofconductive material which is designed to engage with one end of thefilter and cooperate with the inner surface of end cap 52 to hold thefilter in position. Alternatively, the single post 60 can be in the formof two posts one extending from either side of the disc 66. The postprovides the connection between end cap 52 and connector 54 therebyproviding the end to end electrical connection for the structure.

A further alternative form is shown in FIGS. 6 and 7 as filter 20b. Onceagain the design and configuration of the filter is the same as inpreviously discussed embodiments with the difference residing in theform of the conductive path between the end cap 68 at one end and theconductor 70 at the other end. In this embodiment the conductive path isprovided by a group of four spaced suspenders 72, the number ofsuspenders is a matter of choice, which are interconnected at one end bya circular ring 74 so as to form a basket like arrangement. One end ofeach suspender 72 engages with conductive end cap 68 through ring 74 andthe other end of each suspender engages with the conductive connector70. In this manner the end to end conductive path is provided. Thesuspenders are held in position by being contained within a doublemolded clear housing having an outer wall 76 and an inner wall 78.

FIGS. 8 and 9 show another alternative form of filter 20c which onceagain substantially the same as the previously discussed embodimentswith the exception of the form of conductive path extending between endcap 80 and the reduced tip conductive connector portion 82 at the otherend. In this form a centrally located porous conductive cylinder 84 isprovided with one end in direct contact with the conductive end cap 80and the other end in direct contact with a centrally located disc 86 ofconductive material at its other end. The disc is supported andinterconnected with a group of four angularly spaced spokes 88, thenumber of spokes is a matter of choice, which are in turn connected tothe conductive end portion 82. With portions 80, 82, 84, 86 and 88 beingconductive a full conductive pathway is provided from end to end of thefilter while still maintaining the use of a clear housing 90. Thecentral disc 86 cooperates with the inner surface of end cap 80 toretain a filter element 92 in fixed position within the housing.

A further embodiment of the filter is depicted as filter 20d in FIG. 10of the drawings. In all respects the filter operates the same as in thepreviously discussed embodiments with the exception, once again, of theconductive path between the conductive end cap 94 and the opposing endconductive connector 96. In this form, adhered to the outer surface ofthe clear housing 98 is a strip 100 of conductive material. The strip isattached at one end to conductive connector 96 and at the other end toconductive end cap 94 thereby providing the end to end conductive pathfor the filter. The strip can be adhered in any conventional fashion tothe clear housing such as by an epoxy or it can be merely restingadjacent to or on the housing without any direct connection as long asit is connected to the end cap 94 at one end and the connector 96 at theother end.

A final depicted form of filter 20e is depicted in FIG. 11 and is alsosimilar in design to the previous embodiments with the exception of thedesign and positioning of the conductive path between one conductive endcap 102 and the other conductive end connector 104. A clear transparenthousing 106 is employed and positioned inside of the housing is aconductive strip 108 which is closely positioned to the wall of thehousing or adhered thereto by a conventional epoxy or by any othersimilar means as in the previously discussed embodiment. The strip 108is connected at one end to conductive connector 104 and at the other endto conductive end cap 102 thereby providing the end to end continuousconductive path. As previously stated, the strip can be merelypositioned adjacent to the inner wall of transparent housing 106 asdepicted in FIG. 11 or can be adhered directly to the surface as shownwith respect to the embodiment of FIG. 10.

It is also contemplated that the filter could be designed with similarconductive end connections and with the clear conductive housing thatwould be gold filled or contain a grafted conductive surface which wouldprovide the end to end conductive path for the filter.

Thus the several aforenoted objects and advantages are most effectiveattained. Although several somewhat preferred embodiments have beendisclosed and described in detail herein, it should be understood thatthis invention is in no sense limited thereby and its scope is to bedetermined by that of the appended claims.

We claim:
 1. A bacteria filter for use in anesthesiology and respiratoryair systems to filter fluid flow at a desired point in a systemcomprising:an enlarged electrically non-conductive, transparent tubularhousing having a passageway therethrough and having at one end a reducedtip; an electrically conductive connector mounted to the reduced tip; anelectrically conductive end cap affixed to the end of the housing distalfrom the reduced tip; the end cap having an opening therethroughterminating in a projecting end cap connector; a filter element mountedin the housing; an electrically conductive portion extending between theend cap and the electrically conductive connector to provide anelectrically conductive pathway from end to end of the filter includingthe space occupied by the transparent housing; the connector and theprojecting end cap connector being adapted to be mounted within a fluidflow system to permit fluid communication with the interior of thehousing so that fluid flowing through the system passes in one end ofthe housing, through the filter element and out of the other end; theconnector, the housing and the end cap being arranged in a seriesrelationship with means between the connector and the projecting end capproviding a fluid flow from said system through one end of the housing,through the filter element and out of the other end and the electricallyconductive portion being a conductive strip extending from end to end ofthe series relationship and being mounted entirely on the interconnectedhousing, connector, and end cap independent of external supportingstructure; and the electrically conductive portion extending between theend cap and the electrically conductive connector being a conductivestrip of material adhered to the exterior surface of the transparenthousing.